Abstract: An optical system performs a method for measuring an acoustic signal in a wellbore. The optical system includes a light source, an optical fiber and a detector. The light source generates a light pulse. The optical fiber has a first end for receiving the light pulse from the light source and a plurality of enhancement scatterers spaced along a length of the optical fiber for reflecting the light pulse. A longitudinal density of the enhancement scatterers increases with a distance from the first end to increase a signal enhancement generated by the enhancement scatterers distal from the first end. The detector is at the first end of the optical fiber and measures a reflection of the light pulse at the enhancement scatterers to determine the acoustic signal.

Abstract: An optical system employs a method for measuring an acoustic signal in a wellbore. The optical system includes an optical interrogator and an optical fiber. The optical fiber has a plurality of nominal sites uniformly spaced apart along a longitudinal axis of the optical fiber. A plurality of gratings are formed in the optical fiber. Each of the plurality of gratings is associated with a nominal site and is separated from its associated nominal site by an offset distance. The offset distance is selected to reduce a destructive interference between reflections from the plurality of gratings. The optical interrogator transmits a light pulse into the optical fiber to measure the acoustic signal via a reflection of the light pulse from at least one of the plurality of gratings.

Abstract: An optical system performs a method for measuring an acoustic signal in a wellbore. The optical system includes a light source, an optical fiber and a detector. The light source generates a light pulse. The optical fiber has a first end for receiving the light pulse from the light source and a plurality of enhancement scatterers spaced along a length of the optical fiber for reflecting the light pulse. A longitudinal density of the enhancement scatterers increases with a distance from the first end to increase a signal enhancement generated by the enhancement scatterers distal from the first end. The detector is at the first end of the optical fiber and measures a reflection of the light pulse at the enhancement scatterers to determine the acoustic signal.

Abstract: A linear cavity design to produce a traveling wave operation as in a ring laser without the ring cavity design. All fiber configurations may be used to implement fiber lasers based on the linear cavity design.

Abstract: A linear cavity design to produce a traveling wave operation as in a ring laser without the ring cavity design. All fiber configurations may be used to implement fiber lasers based on the linear cavity design.

Abstract: A linear cavity design to produce a traveling wave operation as in a ring laser without the ring cavity design. All fiber configurations may be used to implement fiber lasers based on the linear cavity design.

Abstract: A linear cavity design to produce a traveling wave operation as in a ring laser without the ring cavity design. All fiber configurations may be used to implement fiber lasers based on the linear cavity design.

Abstract: Fiber ring lasers that combine a fiber Fabry-Perot resonator and a fiber grating coupler to produce a single-mode laser output.

Abstract: Techniques and devices using a fiber cavity formed of two spaced fiber gratings to construct a laser frequency locker.